Belt mounted printer hammers movable by shortest distance to indexed position



Mmh 21, 1967 A. L. FIELDER 3 3 6 BELT MOUNTED PRINTER HAMMERS MOVABLE BY SHORTEST DISTANCE T0 INDEXED POSITION Filed Sept. 7, 1965 2 Sheets-Sheet 1 Imvaw-rcna a zgwmww imam 72W RpEvs March 21, 1967 A. FIELDER 3,310,146

BELT MOUNTED PRINTER HAMMERS MOVABLE BY SHORTEST DISTANCE TO INDEXED POSITION Filed Sept. 7, 1965 2 Sheets-Sheet 2 United 3 ,3 1 0,146 Patented Mar. 21, 1 967 fifice 'Alhert Leonard Fielder, Gaiieyyvood, Engiand, assignor to The Marconi Qompany Limited, Engiish Eiectric House, London, Engiand, a British company Filed Sept. '7, 1965, oer. No. 485,315 Claims priority, application Great Britain, ept. if, 1964, 37,264/64 8 Claims. (Ci. 1%749) The invention relates to electro-mechanical printers of the kind having a character-bearing member which carries characters to be printed and which during printing is moved so that the characters continuously and in turn pass a hammer, printing of a particular character being effected by timing the actuation of the hammer to strike When the appropriate character passes, the character being impressed thereby against the paper and an inked ribon. The characters may be the character cyphers carried each on a flat base plate from which they are raised by embossing or engraving, or each character cypher may be recessed into a base plate by punching or engraving, leaving the remainder of the plate raised relative thereto. Such printers find application in, for example, printing the outputs from teleprinters.

When printing a line of characters across a page with a printer of the kind referred to it is necessary to move the hammer across the paper from one character to the next and when the end of a line is reached it is necessary to bring the hammer as quickly as possible back to the line start position. An imaginary line extending across the paper from margin to margin and on which characters are printed is hereinafter termed a print line. Inertial effects limit the speed at which the hamrner can be brought vback to the line start position and thus seriously limit the performance of the printer. It is an object of the invention to provide a printer with improved effective hammer-return time.

According to the invention a printer of the kind referred to comprises at least three hammers spaced apart by the length of a print line on an endless belt which is straight over a portion adjacent the print line, means being provided for advancing the belt, and thus the hammers, by one character space at a time along the print line. It is to be understood that the term endless belt may include any other endless hammer-carrier such as, for example, a chain.

With the arrangement according to the invention only one hammer at a time is adjacent the print line. However, when a hammer reaches the end of the print line there is another hammer ready at the beginning of the line to print the next line and the hammer carriage can continue in the same direction at the same speed. Thus in the usual case when the line of characters ends at the end of the print line (which extends for nearly the whole width of the paper) no change in the hammer drive is necessary. However, it frequently happens that a line of characters ends before the end of the print line (at the end of a paragraph, for example). Preferably therefore there are provided repositioning means which re-position a hammer at the line start position immediately the preceding line of characters has ended, if said line of characters ends before the end of a print line. Further, with the arrangement according to the inven tion it is possible to provide re-positioning means which reverse the direction of belt progress to return the printing hammer to the line start position if at the end of the line of characters it has progressed less than half-way along the print line but which advance the belt to bring the next hammer into the line start position if the printing hammer has progressed more than halfway along the print line. With this arrangement therefore it is never necessary to move the belt suddenly by more than half a print line length.

Preferably the re-positioning means comprise a Wheel coupled to move with the belt one revolution per print line length, an eccentric on the wheel, a solenoid and a connecting rod between the solenoid armature and the eccentric, the innermost position of the solenoid corresponding to a hammer being at the line start position and energisation of the solenoid being effective to draw the armature to its innermost position and thus by acting through the wheel and belt bring back or advance a hammer to the line start position in dependence upon whether the eccentric and armature have not reached or have passed their outermost position.

Preferably the belt is passed around the wheel in frictional contact therewith. The closed loop of the belt is preferably completed around another wheel spaced from the first and which is driven to provide the required hammer traverse, but the drive to which is over-ridden by the action of the re-positioning solenoid.

Each hammer preferably comprises a head carried on a shaft slidably mounted in a passage extending across the width of the belt, the shaft protruding from the side of the belt remote from the hammer head and actuating means being provided for striking the protruding shaft end and thereby operating the hammer. Preferably the actuating means comprises a bar extending parallel to the print line along the length thereof, being movable towards the print line to strike the protruding shaft wherever it should be along the print line. Preferably the hammer shafts and actuating bar are spring loaded in a direction away from the print line.

The character-bearing member may be a rotating drum or disc or a belt carrying raised characters which has a portion moving over the print line in parallel therewith.

The invention will further be described with reference to the accompanying drawings of which:

FIGURE 1 is a side elevation of a printer according to the invention;

FIGURE 2 is a front elevation of the printer of FIG- URE 1;

FIGURE 3 is a perspective view of a hammer of the printer of FIGURES 1 and 2, and

FIGURE 4 is a plan view of the printer of FIGURES 1 and 2. 1

Referring to the figures there is shown a printer having a rotating print drum 1 (see FIGURE 1) on which are embossed sets of characters (not shown). Each set of characters comprises one of each character which may be printed, all the difierent characters of the set being distributed evenly around the circumference of the drum. Each set is only one character width wide and the sets are arranged side by side along the length of the drum. Printing is effected by striking a hammer 2 against an inked ribbon 3 and the paper 4 on which printing is to be effected, the moment of actuation of the hammer being selected so that the appropriate character is struck. As the printed line of characters progresses the hammer is moved along the print line from set to set of characters on the drum 1.

FIGURE 2 shows the mechanism for transporting the hammers. There are three similar hammers, 2, 5, and 6 mounted in a flexible endless belt 7 which is carried by two wheels 8 and 9 arranged so that the belt has a straight portion 10 adjacent the print line of the paper. Wheels 8 and 9 are so dimensioned as to rotate one revolution as the belt 7 moves a distance equal to the length of a print line. As printing progresses, wheel 8 is driven clockwise step by step by a pawl 22 and ratchet 23 fast with the wheel 8 so that the belt moves from left to right one character space at a time. Wheel 9 is driven by the belt. The three hammers are spaced apart around the belt by distances equal to the length of a print line. In the position shown in FIGURE 2, hammer 2 is at the end of the print line and hammer 6 has just arrived at the beginning. Thus it will be seen that the next line of print is commenced by shifting the paper upwards a line space and continuing as before, no change in the direction or speed of movement of the belt 7 and wheels 8 and 9 being necessary, printing merely being effected by means of hammer 6 instead of hammer 2.

In the event that a line of characters is finishedbefore the end of a print line, provision is made to bring a hammer immediately to the line start position (the position of hammer 6 in FIGURE 2). The mechanism for doing this includes a disc 11 mounted on wheel 9 and having an eccentric pivot hole 11a coupled by a connecting rod 12 to a slotted extension 13 of the armature of a solenoid 14. The position shown in full line in the drawing is the innermost position of the armature-that to which the armature is drawn on energisation of the solenoid. It will be seen that in this position a hammer is at the line start position. The position shown in broken line is that normally assumed by the extension 13 and as wheel 9 rotates the end of the connecting rod slides up and down the slot in extension 13. Activation of the solenoid drives wheel 9 and the belt to the innermost position, shown in full line, over-riding the drive to wheel 8. If solenoid 14 is energised before the printing hammer has reached the mid-point of the print line, wheel 9 will have revolved less than half a revolution from the position shown and the wheel and belt will be drawn by the connecting rod backwards so that the printing hammer is brought to the line start position. If, on the other hand the printing hammer has proceeded further than the mid-point of the print line, energisa tion of solenoid 14 will draw the wheels and belt on in the same direction so that the next hammer is stationed at the line start position.

Detail of a hammer is shown in FIGURE 3, from which it will be seen that the hammer comprises a flatfaced head 15 mounted in a recess of a thickened portion of the belt 7. Head 15 is mounted on the end of a shaft 16 which passes through the width of the belt and protrudes from the other side. A spring 17 biasses the hammer head into its recess.

FIGURE 4 shows the means for actuating the hammers as comprising a straight bar 18 mounted parallel to the straight portion 10 of the belt 7 and movable theretowards to strike the shaft 16 of the only hammer which at any one time is opposite the print line. The bar 18 is moved to strike the hammer by the action of a solenoid 19 and is spring biassed clear of the hammer shaft by springs 20 and 21.

I claim:

1. A printer of the kind referred to, comprising an endless belt mounted for movement with a portion thereof extending straight along the print line; at least three hammers mounted on said belt and being spaced apart therealong by the length of a print line; means for driving said belt and said hammers in one direction and thereby successively advancing said hammers by one character space at a time along the print line; and hammer repositioning means operable (1) for reversing the direction of belt drive to return the last hammer which printed to the line start position if, at the end of a printed line of characters, said last printing hammer has progressed less than half way along the print line, and (2) for driving said belt in said one direction to bring the next hammer into the line start position if, at the end of a printed line of characters, said last printing hammer has progressed more than half way along the print line.

2. A printer as claimed in claim 1 and wherein said re-positioning means comprise a wheel coupled to move with the belt one revolution per print line length, an ec'- centric on the wheel, a solenoid and a connecting rod between the solenoid armature and the eccentric, the innermost position of the solenoid corresponding to a hammer being at the line start position and energisation of the solenoid being effective to draw the armature to its innermost position and thus by acting through said connecting rod, said eccentric, said wheel and said belt bring back or advance a hammer to the line start position in dependence upon whether the eccentric and armature have not reached or have passed their outermost position.

3. A printer as claimed in claim 2 and wherein the belt is passed around the wheel in frictional contact therewith.

4. A printer as claimed in claim 3 and wherein the closed loop of the belt is completed around another wheel spaced from the first and which is driven to provide the required hammer traverse, but the drive to which is overridden by the action of the re-positioning solenoid.

5. A printer as claimed in claim 1 and wherein each hammer comprises a head carried on a shaft slidably mounted in a passage etxending across the width of the belt, the shaft protruding from the side of the belt remote from the hammer head, and actuating means being provided for striking the protruding shaft end and thereby operating the hammer.

6. A printer as claimed in claim 5 and wherein the actuating means comprises a bar extending parallel to the print line along the length thereof, being movable towards the print line to strike the protruding shaft wherever it should be along the print line.

7. A printer as claimed in claim 6 and wherein the hammer shafts and actuating bar are spring loaded in a direction away from the print line.

8. A printer as claimed in claim 1 and wherein the character bearing member is a rotating element carrying raised characters which has a portion moving over the print line in parallel therewith.

References Cited by the Examiner UNITED STATES PATENTS 2,656,240 10/1953 Hell 1971 X 2,831,424 4/1958 MacDonald 10193 2,974,634 2/1959 Hense 101-93 2,918,865 12/1959 Wooding 10193 2,927,676 3/1960 Abbondanza 197-6.6 2,936,704 5/1960 Hens-e 10193 2,990,767 7/1961 Demer et al. 101--93 3,007,399 11/1961 Sasaki et al. 10193 3,012,499 12/1961 Amada l01-93 3,041,964 7/1962 Simpson et a1 101-93 3,058,415 10/1962 Hoffman 101--93 3,066,601 12/1962. Eden 10193 3,115,092 12/1963 Sasaki 10193 3,135,195 6/1964 Potter l0 l93 3,144,821 8/1964 Drejza 10193 3,164,084 1/1965 Paige 10193 3,216,348 11/1965 Oldenburg et al. l0l93 3,220,343 11/1965 Wasserman 101-93 3,224,366 12/1965 Cunningham 10l93 3,227,258 l/1966 Pannier et al. 197-6.6

ROBERT E. PULFREY, Primary Examiner.

E, S. BURR, Assistant Examiner. 

1. A PRINTER OF THE KIND REFERRED TO, COMPRISING AN ENDLESS BELT MOUNTED FOR MOVEMENT WITH A PORTION THEREOF EXTENDING STRAIGHT ALONG THE PRINT LINE; AT LEAST THREE HAMMERS MOUNTED ON SAID BELT AND BEING SPACED APART THEREALONG BY THE LENGTH OF A PRINT LINE; MEANS FOR DRIVING SAID BELT AND SAID HAMMERS IN ONE DIRECTION AND THEREBY SUCCESSIVELY ADVANCING SAID HAMMERS BY ONE CHARACTER SPACE AT A TIME ALONG THE PRINT LINE; AND HAMMER REPOSITIONING MEANS OPERABLE (1) FOR REVERSING THE DIRECTION OF BELT DRIVE TO RETURN THE LAST HAMMER WHICH PRINTED TO THE LINE START POSITION IF, AT THE END OF A PRINTED LINE OF CHARACTERS, SAID LAST PRINTING HAMMER HAS PROGRESSED 